* [PATCH bpf-next] bpf: fix incorrect kmalloc usage in lpm_trie MAP_GET_NEXT_KEY rcu region
@ 2018-01-23 6:53 Yonghong Song
2018-01-23 15:50 ` Eric Dumazet
0 siblings, 1 reply; 3+ messages in thread
From: Yonghong Song @ 2018-01-23 6:53 UTC (permalink / raw)
To: ast, daniel, netdev; +Cc: kernel-team
In commit b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map"),
the implemented MAP_GET_NEXT_KEY callback function is guarded with rcu read lock.
In the function body, "kmalloc(size, GFP_USER | __GFP_NOWARN)" is used which may
sleep and violate rcu read lock region requirements. This patch fixed the issue
by using GFP_ATOMIC instead to avoid blocking kmalloc. Tested with
CONFIG_DEBUG_ATOMIC_SLEEP=y as suggested by Eric Dumazet.
Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
Signed-off-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/lpm_trie.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
index d7ea962..8f083ea 100644
--- a/kernel/bpf/lpm_trie.c
+++ b/kernel/bpf/lpm_trie.c
@@ -624,7 +624,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
}
node_stack = kmalloc(trie->max_prefixlen * sizeof(struct lpm_trie_node *),
- GFP_USER | __GFP_NOWARN);
+ GFP_ATOMIC | __GFP_NOWARN);
if (!node_stack)
return -ENOMEM;
--
2.9.5
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH bpf-next] bpf: fix incorrect kmalloc usage in lpm_trie MAP_GET_NEXT_KEY rcu region
2018-01-23 6:53 [PATCH bpf-next] bpf: fix incorrect kmalloc usage in lpm_trie MAP_GET_NEXT_KEY rcu region Yonghong Song
@ 2018-01-23 15:50 ` Eric Dumazet
2018-01-23 16:35 ` Daniel Borkmann
0 siblings, 1 reply; 3+ messages in thread
From: Eric Dumazet @ 2018-01-23 15:50 UTC (permalink / raw)
To: Yonghong Song, ast, daniel, netdev; +Cc: kernel-team
On Mon, 2018-01-22 at 22:53 -0800, Yonghong Song wrote:
> In commit b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map"),
> the implemented MAP_GET_NEXT_KEY callback function is guarded with rcu read lock.
> In the function body, "kmalloc(size, GFP_USER | __GFP_NOWARN)" is used which may
> sleep and violate rcu read lock region requirements. This patch fixed the issue
> by using GFP_ATOMIC instead to avoid blocking kmalloc. Tested with
> CONFIG_DEBUG_ATOMIC_SLEEP=y as suggested by Eric Dumazet.
>
> Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
> Signed-off-by: Yonghong Song <yhs@fb.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Thanks.
> ---
> kernel/bpf/lpm_trie.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
> index d7ea962..8f083ea 100644
> --- a/kernel/bpf/lpm_trie.c
> +++ b/kernel/bpf/lpm_trie.c
> @@ -624,7 +624,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
> }
>
> node_stack = kmalloc(trie->max_prefixlen * sizeof(struct lpm_trie_node *),
> - GFP_USER | __GFP_NOWARN);
> + GFP_ATOMIC | __GFP_NOWARN);
> if (!node_stack)
> return -ENOMEM;
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH bpf-next] bpf: fix incorrect kmalloc usage in lpm_trie MAP_GET_NEXT_KEY rcu region
2018-01-23 15:50 ` Eric Dumazet
@ 2018-01-23 16:35 ` Daniel Borkmann
0 siblings, 0 replies; 3+ messages in thread
From: Daniel Borkmann @ 2018-01-23 16:35 UTC (permalink / raw)
To: Eric Dumazet, Yonghong Song, ast, netdev; +Cc: kernel-team
On 01/23/2018 04:50 PM, Eric Dumazet wrote:
> On Mon, 2018-01-22 at 22:53 -0800, Yonghong Song wrote:
>> In commit b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map"),
>> the implemented MAP_GET_NEXT_KEY callback function is guarded with rcu read lock.
>> In the function body, "kmalloc(size, GFP_USER | __GFP_NOWARN)" is used which may
>> sleep and violate rcu read lock region requirements. This patch fixed the issue
>> by using GFP_ATOMIC instead to avoid blocking kmalloc. Tested with
>> CONFIG_DEBUG_ATOMIC_SLEEP=y as suggested by Eric Dumazet.
>>
>> Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
Applied to bpf-next, thanks everyone!
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-01-23 6:53 [PATCH bpf-next] bpf: fix incorrect kmalloc usage in lpm_trie MAP_GET_NEXT_KEY rcu region Yonghong Song
2018-01-23 15:50 ` Eric Dumazet
2018-01-23 16:35 ` Daniel Borkmann
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